Propellant powder



e Patented July 23, 1935 a I UN ATES PATENT OFFICE PROPELLAN T POWDER William E. Wagner, Kilworthy, Ontario, Canada, I assignor to Western Cartridge Company, East Alton, 111., a corporation of Delaware No Drawing. Application December 8, 1930, Serial No. 500,876. Renewed March 24, 1934 Claims. (Cl. 52-13) This invention relates to propellant powders, Such treatment with a deterrent is effective and more particularly to powders of the double. to retard the initial combustion rate ofIthe powbase type, such as nitrocellulose-nitroglycerin der substantially and-thus render the same propowders. gressive burning. By the expression retard, the

5 One of the objects of this invention is to proinitial combustion rate substantially as used 5 vide a double base propellant powder which is so herein and in the appended claims is meantthat treated as to improvelts ballistic characteristics. combustion of the outer layers of the powder grain Another object is to provide a double base is distinctly slowed by the action of the deterrent powder which is so treated that the rate at which material soth'at the outer layers of the grain the gas is evolved will progressively increase as bummore slowly than the unaffected or less af- 10 the powder-is consumed. fected interior of the grain, and also that the Further objects will appear from the detail outer layers burn more slowly than if they had description, in which will be specifically described been acted upon with a. simple solvent having 1 a, number .of illustrative embodiments of this no definite slowing action. v

" invention; it is tobe understood, however, that As an illustrative embodiment of this inven- 15 this invention is susceptible of various other emtion, a double-base powder containing 15% nitrobo'diments. v glycerin, produced in any manner well known to Generally stated, adouble base powder is treatthose skilled in the art, is surface treated with ed with a suitable deterrent and in such a man- 6% of diamyl phthalate. Such a powder, adapther as to-secure the desired ballistic. properties; ed more particularly for use in rifle cartridges 20 and in accordance with the illustrative embodiof small calibre, may have grains in. the form ments of this invention, this deterrent is of a type of flat discs .050-.075 mm, thick and .90 mm. in which is a solvent for the powder grain. In the diameter. I

, process-of treatment, the deterrent iscarried in A number of embodiments of this invention a vehicle through the medium of which the dewill now be described.

terrent is applied to and even carried into the Adouble base powder of the character described grains, and the vehicle may then be extracted. is treated with a solution of diamyl phthalate in The vehicle may be of a type which is a solvent benzol, benzol being a solvent for the deterrent e for the deterrent, or a solvent for one or both-of and also for the nitroglycerin, but a non-solvent I 3 the bases of the double base powder. This veforthe mtr.ocellulose. For this purpose, to 100 hicle may also be one which is volatile, so that parts by weight of powder are added 70 parts by the extraction of the vehicle from the treated weight of a 6.75% solution of diamyl phthalate in powder grains may be secured by evaporation. benzol, preferably in a rotating barrel connected The double base powder grain may be comwith a. solvent recovery system. The deterrent posed of nitrocellulose and nitroglycerin, in which will be carried into the grain and as the .vehicle is 35 the nitroglycerin content is such as to secure the driven off, the deterrent will be left in the grain.

desired ballistic properties. For example, where After the grain is dried, it can be graphited in the powder is particularly adapted for use as a rifle usual manner.

powder, the nitroglycerin content may be 15%. In accordance with another embodiment of this 40 The deterrent may be one of the usual ones eminvention, there is employed a vehicle or carrier 40 ployed; a deterrent which, however, has been which is a solvent only for the deterrent, while found to be particularly useful in diamyl phthalbeing a non-solvent for both of the bases of the ate; a related deterrent, such as dibutyl phthaldouble base powder grain; 'suchavehicleiscarbon ate, may also be employed. Moreover, other detetrachloride, which is a. solvent for diamyl 5 terrents, such as tricresyl phosphate, ethyl lacphthalate, but is a. non-solvent for both nitrotate, dimethyl diphenylurea, diethylene glycol (11- cellulose and nitroglycerin. The procedure may nitrate, andany one of the mono nitro, dinitro be generally carried. out as described in the preand trinitro toluenes may be employed. The proceding embodiment, and upon volatilization of portion of the deterrent may be from 2 to 8% the carrier, the deterrent will be left on the relative the double base powder. It is desirable powder grain. In this case, not only is the solu- 50 that the double base powder grain contain its tion of either 01 the bases of the powder grain original nitroglycerin content as distinguished avoided, but since the vehicle is of the non-infrom a grain in which a part of the nitroglycerin flammable, although volatile, type, the fire hazhas been extracted from the grain prior to the ard is considerably reduced. 65 application of the deterrent. In accordance-with another embodiment of this invention, the vehicle or carrier employed is one which is a solvent for both nitrocellulose and nitroglycerin, as well as for diamyl phthalate; an

example of such a vehicle is methyl alcohol. Now, 7

vmaterial solution oijthe grain bases be avoided,

but softening of the grains can be prevented to an extent sufiicient to avoid adhesion or sticking together of the grains. This may be accomplished by employing only sumcient of the vejhicle to just barely wet the grain surfaces, followed by evaporation of the, vehicle. By adding water to the alcohol, the vehicle may be brought to a point where very little of even the nitroglycerin base will be extracted, while the solvent ac-' tion with reference to the deterrent will be still maintained. The deterrent carried by the vehicle;

may be applied as previously described in connection with the other embodiments, the vehicle being driven off by heat: however, the alcohol can be removed in an excess of water. Here, again, the solvent vehicle will secure penetration of the deterrent into the grain; however, by con: trol of the process, the will not be softened to a point where they will adhere or stick together before the solvent is driven off.

In" accordancewith another embodiment ofthis invention, the vehicle may be composed of a mixture of a solvent and a non-solvent of nitrocellulose, such as ethyl acetate and benzol, -in such proportions as to hold the deterrent in solution, but so as not to actively attack the nitrocellulose sufliciently to cause the grains to adhere one-to the other. Similarly, a solution of thedeterrent .in the alcohol vehicle may haveadded thereto a small amount of ethyl acetate-to secure the desired result. I r

Where the vehicle or carrier employed is a volatile one and of the inflammable type, the evaporation temperature may be kept down to a point required for safety. Evaporation may be accomplished at reduced temperatures under vacuum, or with large excess of air to eliminate dangerof explosive mixtures. c

There is thus produced a powder grain, and

more particularly a double'base powder "grain, which not only has the desired ballistic properties, butfwhich can be made progressive burning to' the desired extent. The progressive burning characteristic imparted to the powder allowsthe powder charge of the cartridge to be increased withoutincreasing the maximum pressure, resulting in much higher velocities without any increase in pressure; at the same time the nitroglycerin content imparts to the interior of the grain a fastburning characteristic.

While this invention is particularly applicable to nitrocellulose nitroglycerin, gelatiniaers-ior nitrocellulose other than nitroglycerin may be employed, such as nitrates of polyglycerin, or any of the glycols or polyglycols, or nitrates of any 0! the aromatic series. It will further be understood that, various features and sub-combinations are of utility and may be employed without reference to other features and sub-combinations; that is contemplated by and is within the scope or the appended claims. It will further be understood that various changes may be made in details with'out departing from the spirit or this invention; it is therefore to be understood that this inventionis'not to be limitedtothe specific details described;

"Having thus described claimed is: v I

1. 'A double base propellant powder which is surface-treated with a dialkyl-phthalate to an extent sufficient to retard the initial combustion rate and render the grains progressive burning.

'2. A double base propellant powder containing about 15% of nitroglycerin and surface-treated the invention, whatiisf with a dialkyl-phthalate to an extent suflicient'to retard the initial combustion rate and render the grains progressive burning.

. 3. A double base pr derwhich, surface-treated with diamyl phthalate to an I tent sufficient to retard the initial combustion rate andrender the grains progressive burning.

4. A propellant powder grain composed-ornitrocellulose incorporated with a gelatinizer therefor, and containing sufiicient 01' a dialkyl phthalate concentrated near its surfaceto retard thein'itial combustion-rate and render the grain progressive burning. a

' 5. A propellant powder'grain composed of nitrocellulose incorporated 'with-a sufhcient of a gelatinizer to render the same dense and hard,

and containing in addition'to the said gelatinizer suflicient of a dialkyl phthalate concentrated near its surfaceto retard the initial combustion rate progressive burning-.

and render the grain WILLIAM E. WAGNER. 

